Why does my volume keep turning lower with out telling me?

My Samsung s7 active keeps Turing the "Media" volume down, with out letting me know, so when it does happen I CAN NOT see the white bar like when I do it manualy. Instead, for example if I am watching a YouTube video the volume will turn down it self, not letting me know. I have even tested this many many times. I have put it on the hight volume and waited for a few minutes, then manually turn it down and up, it would land somewhere else, if it hasn't turned down it would still be full. Even as I typed this I am listening to music and it just turned down, I can even hear the impact. I have even down it where it's on the volume 1, the last one, and it suddenly turns off. This has been happening for about 3 days and it has been pissing me off. I do not press it off on accident. I have seen people ask things and a lot of responses were, "IS it sticky?" "Did you press it accidentally?" And I answer for myself and I do not, do any of thoes. Please, if anyone can reply. Thank you.